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Expanded CAG repeats in coding regions of different genes are the most common cause of dominantly inherited spinocerebellar ataxias (SCAs). These repeats are unstable through the germline, and larger repeats lead to earlier onset. We measured somatic expansion in blood samples collected from 30 SCA1, 50 SCA2, 74 SCA3, and 30 SCA7 individuals over a mean interval of 8.5 years, along with postmortem tissues and fetal tissues from SCA1, SCA3, and SCA7 individuals to examine somatic expansion at different stages of life. We showed that somatic mosaicism in the blood increases over time. Expansion levels are significantly different among SCAs and correlate with CAG repeat lengths. The level of expansion is greater in individuals with SCA7 who manifest disease compared to that of those who do not yet display symptoms. Brain tissues from SCA individuals have larger expansions compared to the blood. The cerebellum has the lowest mosaicism among the studied brain regions, along with a high expression of ATXNs and DNA repair genes. This was the opposite in cortices, with the highest mosaicism and lower expression of ATXNs and DNA repair genes. Fetal cortices did not show repeat instability. This study shows that CAG repeats are increasingly unstable during life in the blood and the brain of SCA individuals, with gene- and tissue-specific patterns., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: CAG/CAA repeat expansions in TBP >49 are responsible for spinocerebellar ataxia (SCA) type 17 (SCA17). We previously detected cosegregation of STUB1 variants causing SCA48 with intermediate alleles of TBP in 2 families. This cosegregation questions the existence of SCA48 as a monogenic disease., Methods: We systematically sequenced TBP repeats in 34 probands of dominant ataxia families with STUB1 variants. In addition, we searched for pathogenic STUB1 variants in probands with expanded alleles of TBP >49 (n = 2) or intermediate alleles of TBP ≥40 (n = 47)., Results: STUB1 variants were found in half of the TBP 40-49 cohort. Mirroring this finding, TBP 40-49 alleles were detected in 40% of STUB1 probands. The longer the TBP repeat length, the more likely the occurrence of cognitive impairment (P = .0129) and the faster the disease progression until death (P = .0003). Importantly, 13 STUB1 probands presenting with the full SCA48 clinical phenotype had normal TBP 37-39 alleles, excluding digenic inheritance as the sole mode., Conclusion: We show that intermediate TBP 40-49 alleles act as disease modifiers of SCA48 rather than a STUB1/TBP digenic model. This distinction from what has been proposed before has crucial consequences for genetic counseling in SCA48., Competing Interests: Conflict of Interest The authors declare no conflicts of interest., (Copyright © 2022 American College of Medical Genetics and Genomics. Published by Elsevier Inc. All rights reserved.)

Neonatal Diabetes (ND) mellitus is a rare genetic disease (1 in 90,000 live births). It is defined by the presence of severe hyperglycaemia associated with insufficient or no circulating insulin, occurring mainly before 6 months of age and rarely between 6 months and 1 year. Such hyperglycaemia requires either transient treatment with insulin in about half of cases, or permanent insulin treatment. The disease is explained by two major groups of mechanism: malformation of the pancreas with altered insulin-secreting cells development/survival or abnormal function of the existing pancreatic β cell. The most frequent genetic causes of neonatal diabetes mellitus with abnormal β cell function are abnormalities of the 6q24 locus and mutations of the ABCC8 or KCNJ11 genes coding for the potassium channel in the pancreatic β cell. Other genes are associated with pancreas malformation or insufficient β cells development or destruction of β cells. Clinically, compared to patients with an ABCC8 or KCNJ11 mutation, patients with a 6q24 abnormality have lower birth weight and height, are younger at diagnosis and remission, and have a higher malformation frequency. Patients with an ABCC8 or KCNJ11 mutation have neurological and neuropsychological disorders in all those tested carefully. Up to 86% of patients who go into remission have recurrent diabetes when they reach puberty, with no difference due to the genetic origin. All these results reinforce the importance of prolonged follow-up by a multidisciplinary pediatric team, and later doctors specializing in adult medicine. 90% of the patients with an ABCC8 or KCNJ11 mutation as well as those with 6q24 anomalies are amenable to a successful switch from insulin injection to oral sulfonylureas., (Copyright © 2020 Beltrand, Busiah, Vaivre-Douret, Fauret, Berdugo, Cavé and Polak.)

Vascular Ehlers-Danlos syndrome (vEDS) is a rare and severe autosomal dominant disorder caused by variants at the COL3A1 gene. Clinical characteristics and course of disease of 215 molecularly proven patients (146 index cases and 69 relatives) were analysed. We found 126 distincts variants that were divided into five groups: (1) Glycine substitutions (n=71), (2) splice-site and in-frame insertions-deletions (n=36), (3) variants leading to haplo-insufficiency (n=7), (4) non-glycine missense variants within the triple helix (n=4 variants), and (5) non-glycine missense variants or in-frame insertions-deletions, in the N- or C-terminal part of the protein (n=8). Overall, our cohort confirmed the severity of the disease with a median age at first complication of 29 years (IQR 22-39), the most frequent being arterial (48%) and digestive (24%) ruptures. Groups 2 and 1 were significantly more severe than groups 3-5, with extreme median ages at first major complication of 23-47 years. Patients of groups 3-5 had a less typical phenotype and remarkably absence of digestive events. The distribution of glycine-replacing amino acids was strongly biased towards more destabilizing residues of the collagen assembly. Thus the natural course of vEDS and the clinical phenotype of patients are influenced by the type of COL3A1 variant. This study also confirms that patients with variants located in the C- and N-termini or leading to haplo-insufficiency have milder course of the disease and less prevalent diagnostic criteria. These findings may help refine diagnostic strategy, genetic counselling and clinical care.

Background: Vascular Ehlers-Danlos syndrome is a rare severe disease that causes arterial dissections and ruptures that can lead to early death. No preventive treatment has yet been validated. Our aim was to assess the ability of celiprolol, a β(1)-adrenoceptor antagonist with a β(2)-adrenoceptor agonist action, to prevent arterial dissections and ruptures in vascular Ehlers-Danlos syndrome., Methods: Our study was a multicentre, randomised, open trial with blinded assessment of clinical events in eight centres in France and one in Belgium. Patients with clinical vascular Ehlers-Danlos syndrome were randomly assigned to 5 years of treatment with celiprolol or to no treatment. Randomisation was done from a centralised, previously established list of sealed envelopes with stratification by patients' age (≤32 years or >32 years). 33 patients were positive for mutation of collagen 3A1 (COL3A1). Celiprolol was administered twice daily and uptritrated by 100 mg steps every 6 months to a maximum of 400 mg per day. [DOSAGE ERROR CORRECTED]. The primary endpoints were arterial events (rupture or dissection, fatal or not). This study is registered with ClinicalTrials.gov, number NCT00190411., Findings: 53 patients were randomly assigned to celiprolol (25 patients) or control groups (28). Mean duration of follow-up was 47 (SD 5) months, with the trial stopped early for treatment benefit. The primary endpoints were reached by five (20%) in the celiprolol group and by 14 (50%) controls (hazard ratio [HR] 0·36; 95% CI 0·15-0·88; p=0·040). Adverse events were severe fatigue in one patient after starting 100 mg celiprolol and mild fatigue in two patients related to dose uptitration., Interpretation: We suggest that celiprolol might be the treatment of choice for physicians aiming to prevent major complications in patients with vascular Ehlers-Danlos syndrome. Whether patients with similar clinical presentations and no mutation are also protected remains to be established., Funding: French Ministry of Health, Programme Hospitalier de Recherche Clinique 2001., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Lymphedema-distichiasis (LD) syndrome is a rare autosomal dominant disorder of the FOXC2 gene, which codes for a forkhead transcription factor. Most of the mutations described in this gene to date are deletions or insertions, suggesting a mechanism of haploinsufficiency. We studied three independent families with LD presenting with both lymphedema and distichiasis. Two microrearrangements (one 8-bp deletion and one 7-bp duplication) occurring in a GC-rich genomic region (c.893-930) known to be prone to mutations were identified. A new missense mutation (p.Lys132Glu) located in a highly conserved sequence, the forkhead domain, was also identified. Mutations in this domain have been previously shown to impair FOXC2 transactivation ability. At a genetic level, this study confirms the heterogeneity of mutations responsible for LD and is consistent with a mechanism of haploinsufficiency. At a clinical level, it reinforces the importance of genetic testing in subjects with familial lymphedema or distichiasis, since measures can be taken at an early stage to prevent complications and to reduce the progression of lymphedema or delay its occurrence.

Objective: Trisomy of chromosome 13, 18, 21 and sex chromosome aneuploidies are the most common chromosomal abnormalities encountered in prenatal screening and are responsible for polymaformative syndrome associated with severe mental retardation. This high degree of morbidity justifies the prenatal diagnosis of these aneuploidies. Fetal nuchal translucency measurement and maternal serum biochemical marker assessment are the method of choice used for antenatal screening of aneuploidies. This prenatal screening leads to numerous maternal samplings followed by karyotyping which is cost-effective, time consuming, while results are generally returned between 2 and 3 weeks. Our study describes the research of common aneuploidies by molecular biology. We have used on one hand the MLPA kit (MRC Holland) based on amplification of specific DNA probes that hybridize with chromosomes 13, 18, 21, X, Y. On the other hand we have developed multiplex fluorescent PCR, amplifying microsatellite DNA sequences., Patients and Methods: We have evaluated the efficiency of these two techniques to detect chromosomal abnormalities by screening 400 amniotic fluids or chorionic villi samples obtained from pregnant women presenting a high risk of chromosomal aneuploidy., Results: We have found four trisomies 21, one trisomy 13, one monosomy 13, one trisomy 18, two triploidies, one trisomy X and one Klinefelter syndrome., Discussion and Conclusion: In our study we have detected by molecular biology, in less than 48 h, 100% of common chromosomal aneuploidies without false positive or false negative results which could lead molecular biology as a method of choice for the rapid detection of common aneuploidies in addition to fetal karyotyping.